Exam 3 Part 2 Flashcards
Microtubule dynamtic instability
uses a GTP/GDP switch - protein hydrolyzes GTP to GDP (Rab proteins)
growing microtubule is being added faster that hydrolysation, shrinking microtubule growth is slower than hydrolation
stabilization of microtubules
stablized at one end by y tubulin
growing end attaches to a microtubule capping protein that stabilizes on other side
railroad tracks
microtubule polarity
allows for directional transport
dyein
walks toward microtubule minus end
kinesin
walks toward microtubule plus end
motor protein cargo
could be an organelle, vesicle, or large macromolecule
movement of motor protein
uses ATP hydrolysis for a 3x conformational change
ingredients for mircotubule movement
ATP
microtubules
kinesin/dynein
cilia locations
line the respiratory tract, brain ventricles, trachea, kidneys, fallopian tubes
microtubule movement
dynein moves the microtubule
in cilia and flagella, microtubules are linked for bending
walking causes the bending (not all move with the bend)
cilia/flagellum microtubule structure
9+2
9 doublets outside, 2 singlets inside
dynein has one leg on outside of circle, and one leg in
actin filamens
maintenance of shape and contraction
microvilli, stress fibers, lammellopodia, cell division
actin filament structure
thin and flexible, some polarity
not as rigid as microtubules
have a plus and minus end (adds preferentially to plus end)
Dynamic instability of actin filaments
ADP/ATP switching causes instability
usually looses at ADP side and gains at ATP side, but still can add at either side
no organisation center
treadmilling
constant polymerization and depolymerization of actin filaments causes the filament to continue to be the same length
GTP cap
on actin filaments, caps plus end to continue growth, loss of it causes catastrophic shrinkage
actin filament functions
interactions with other proteins are necessary
ex. binding proteins, myosin motor proteins, side-binding proteins, capping proteins, cross-linking proteins, severing proteins, monomer-sequestering proteins
actin in cell cortex
attached to transmembrane prtoeins and attachment proteins
cell crawling
facilitated by actin - actin polymerization at plus end protrudes lamellipodium, myosin motor proteins slide actin filaments of rest of cell toward lamell., lamell attaches to substrate with focal contacts (integrins)
integrins
attach lamellipodium to surface
cell migration
cell testing its surroundings, facilitated by actin using filopodium
filopodium
actin filaments in cell migration - smaller, more directional than lamellipodium
leading edge
during cell migration, actin filametns can build off each other at 70 angles
